In a crucial breakthrough in the sensational Tihar Jail escape case, the Delhi police has arrested the person who posed as a cop and helped Sher Singh Rana, alleged killer of dacoit-turned-politician Phoolan Devi, escape from the high-security prison on February 17.

Phoolan Devi was gunned down outside her official residence at Ashoka Road in Delhi on July 25, 2001.

The police also arrested Sher Singh Rana's brother, Vikram, and claim to have unravelled the entire conspiracy.

Vikram hatched the escape plan in November 2003 after Rana apprehended that he could face the death sentence considering the way the trial in the case was going, Additional Commissioner of Police (Special Cell) Karnal Singh told a press conference in Delhi.

They roped in Sandeep Thakur, a resident of Rana's hometown Roorkee, who had no regular means of income and no known criminal background. He was to be paid Rs 600,000 to pose as constable Arvind Kumar of the Delhi Armed Police (3rd Battalion).

Thakur had met Rana in jail four times by posing as advocate Pradeep Kumar and once by posing as a friend called Ravi.

As part of the plan, Thakur met Sher Singh Rana in the jail a day before of the escape by posing as Pradeep Kumar and discussed the details. He then stayed overnight at a pre-identified place in Ghaziabad. He had bought the police uniform and handcuff from Roorkee for Rs 5,000, which was paid by Vikram.

On February 17, when Rana was scheduled to appear in a court in Haridwar (Uttaranchal), Thakur reached Tihar wearing in police uniform at around 0655 IST in an autorickshaw.

Already briefed about the procedures involved, Thakur went to Jail No 1 posing as constable Arvind Kumar and sought Rana's custody for production in the Haridwar court.

When Rana was handed over to him, the 'fake' constable handcuffed him, collected Rs 40 as diet allowance for the undertrial after filling a form.

Both of them then walked out, boarded the waiting autorickshaw and headed to the Inter-State Bus Terminus at Kashmere Gate. They caught a bus to Ghaziabad from where they parted ways.

A Delhi police (Special Cell) team headed by Assistant Commissioner of Police Shibesh Singh Thakur nabbed Thakur from his 'place of hiding' in a village in Meerut district in Uttar Pradesh on Saturday evening.

Thakur met Rana once after the escape, Karnal Singh said.

Vikram was arrested from his home in Roorkee after Thakur revealed his role in the escape. The police have now got some clues about Rana but are not divulging any details.

Significantly, soon after the escape, Vikram claimed to have received a call from his brother who rebuked him for 'not defending him properly'.

Karnal Singh confirmed Rana had made the call about an hour after the escape from an STD booth, which has been traced, but claimed it was made for arranging money for the 'imposter'.

Contradicting earlier versions, the Additional CP said the 'impersonator' had shown no court production documents or I-card at Tihar Jail while seeking Rana's custody, raising questions over the conduct of the officials and personnel on duty at that time.

"Prima facie, it appears that no jail official was present and Rana was handed over (to Thakur) by undertrials," Karnal Singh said. "We are interrogating jail officials to ascertain whether it was just a lapse or any of them (officials) was involved (in helping Rana escape)," he added.

Vikram and Thakur were produced before a court in Delhi on Sunday and sent to 10 days' police remand.

Meanwhile, the Uttaranchal police on Sunday said in Dehra Dun that the Special Crime Branch of the Delhi police has picked up a contractor, Paras Kumar, from Roorkee in Hardwar district for questioning in connection with the Rana's escape. Roorkee Deputy Superintendent of Police Mohan Singh Rawat said that a possible encounter between the Delhi police and their Uttaranchal counterparts was averted when the contractor was being taken away.

The Delhi police personnel were taking the contractor away without informing the local police. Uttaranchal police chased the vehicle of the Delhi police personnel after the contractor's brother filed an FIR saying that his brother had been abducted by some unknown persons when they were traveling by a motor cycle.

The Delhi police is conducting raids at several areas in and around Roorkee to trace Rana, Rawat said.